Rheumatoid Arthritis-Associated Interstitial Lung Disease Mortality Trends in the United States: A Population-Based Analysis (1999–2020)

Abstract

Objective: To evaluate long term trends and demographic, racial, and geographic disparities in mortality related to rheumatoid arthritis associated interstitial lung disease (RA-ILD) in the United States from 1999 to 2020. Methods: Mortality data were taken from the CDC WONDER Multiple Cause of Death database for individuals aged 15 and older. Deaths were included if both ICD-10 codes for rheumatoid arthritis (M05–M06) and interstitial lung disease with fibrosis (J84.1) were recorded; juvenile RA (M08.0) was excluded. Age-adjusted mortality rates (AAMRs) per 100,000 individuals were computed using the 2000 U.S. standard population. Trends were analysed through average and segmented annual percent changes (AAPC, APC) by sex, age, race/ethnicity, geography, and rural urban classification. Results: Between 1999 and 2020, there were 10,171 RA-ILD related deaths. The overall AAMR was 0.2 per 100,000, declining from 0.2 in 1999 to 0.1 in 2020 (AAPC –3.08; 95% CI –4.79 to –2.28; p<0.01). Females represented 63.5% of deaths, exhibiting higher AAMRs than males (0.2 versus 0.1). American Indian/Alaska Native individuals had the highest mortality rate (0.5), while non-Hispanic Black and Asian/Pacific Islander groups had the lowest (0.1). The most significant decline occurred from 2014 to 2017 (APC –24.09; p<0.05). Geographic disparities persisted, especially in northern and western states. Conclusion: Mortality from RA-ILD has decreased over the past two decades, particularly post 2014, likely due to enhanced management and early detection of ILD. However, ongoing gender, racial, and regional disparities emphasise the necessity for equitable healthcare access.